(1) Field of the Invention
The present invention relates to a method for processing silver halide photographic lightsensitive materials and in particular to a method for processing silver halide photographic materials, which makes it possible to reduce the amount of waste liquor and to make effective use of agents in processing solutions.
(2) Prior Art
It has been proposed to reduce the amount of washing water used in water washing and other processes for processing silver halide photographic lightsensitive materials, in view of environmental protection, exhaustion of water resources and enhanced economy. For example, one of such techniques for reducing the amount of washing water is proposed by S. R. Goldwasser in his article entitled "Water Flow Rates in Immersion-Washing of Motion Picture Film", Journal of the Society of Motion Picture and Television Engineers, 1955, Vol. 64, pp. 248-253 in which saving of the amount of washing water is achieved by employing a multistage washing system including the use of a plurality of washing tanks and countercurrently passing water therethrough. This method has been adopted in different kinds of automatic processors as an effective means for water-saving.
According to this multistage countercurrent system, the amount of water to be supplied can be reduced as the number of water washing baths is increased. However, the increase in the number of water washing baths leads to an increase in the space occupied by the automatic processors and, therefore, the number of water washing or stabilization baths in such a multistage countercurrent system is in general 2 to 6 and in most cases 2 to 4.
Moreover, Japanese Patent Un-examined Publication (hereinafter referred to as J. P. KOKAI) No. 57-8543 discloses a method which makes it possible to stabilize images and to save washing water by processing the lightsensitive material with stabilization baths having stabilization effect under the multistage countercurrent system after the water washing process is carried out under the multistage countercurrent system.
However, this method also suffers from a problem that even if such stabilization baths are used, the number of baths must be increased to achieve water-saving effect. Therefore, this method does not satisfy the requirements in this field.
If washing water is substantially saved without increasing the number of water washing or stabilization baths, this entrains various troubles, for instance, there is a tendency of causing adhesion between processed lightsensitve materials and the discolorlation of images becomes extremely high due to the increase in the concentration of components contained in the preceding bath, such as a fixing or bleaching-fixing bath components, in the washing or stabilization solution. In order to eliminate such troubles, J. P. KOKAI Nos. 58-105150 and 60-241053 disclose methods in which an apparatus for reverse osmosis is employed as a means for water-saving without increasing the number of water washing or stabilization baths.
In these methods, the overflow from water washing or stabilization baths is directly transferred to such an apparatus for reverse osmosis and the liquid passed therethrough is supplied to water washing or stabilization baths, while the concentrated liquid which remains therein is fed to a bleaching-fixing bath or an apparatus for recovering silver. However, this method is practically carried out without using a large apparatus provided with a pump capable of applying a high pressure to a membrane for reverse osmosis, having a large area. It is therefore quite difficult to sufficiently reduce the amount of liquid concentrated and discharged from the reverse osmosis apparatus (hereunder referred to as the concentrated solution) with respect to the amount of clean solution passing through the membrane for reverse osmosis (hereinafter referred to as the membrane-permeated solution). Using the large apparatus requires a huge initial investment.
On the other hand, J. P. KOKAI No. 60-235133 describes a method in which the overflow from water washing and stabilization process is used in the preceding bath having fixing ability for the purposes of saving water and reducing the overall waste liquor.
This method can serve to lower the production cost since the components of the preceding bath carried over to the stabilization process by the lightsensitive material in the absorbed state can be recycled.
However, if this method is carried out using an automatic processor for a long period of time, conveyor rollers, squeeze blades or the like of the automatic processor at the portions corresponding to baths having fixing ability and the following stabilization baths are extremely stained and collect deposits thereon. This results in various troubles such as the contamination of lightsensitive materials and the formation of defects thereon.
Commonly, it is necessary to add to the stabilization bath such an antibacterial or antifungus agents as 5-chloro-2-methyl-4-isothiazolin-3-one and such a chelating agent as 1-hydroxyethylidene-1,1-diphosphonic acid. However, the use of these additives is often accompanied by the aforementioned troubles and may possibly impair the quality of the preceding bath. On the contrary, if the overflow from a water washing process in which city water is used and saved is introduced into the preceding bath, a severe problem is caused. Specifically, bacteria and/or mold severely proliferate in each bath for water washing process and adhere to the lightsensitive material pass therethrough. Moreover, the conveyor rollers, squeeze blades and the like are contaminated and collect deposits, while bacteria and mold proliferate thereon simultaneously. Thus, the commercial value of the processed lightsensitive material is extremely lowered. Therefore these methods cannot be adopted practically.
As explained above, it is important to introduce the overflow from water washing and/or stabilization processes into the preceding bath in view of water-saving, reduction of the amount of waste liquor and effective use of the components of processing solutions. Nevertheless, such processes have not yet been effected practically because of the aforementioned problems.